When examining a patient or preparing for surgery, in particular surgery in the region of bones such as, for example, spine, hip joint or knee operations, x-ray recordings or computer tomography (CT) recordings of the affected body structure are taken. From these recordings, the body structures can be clearly displayed. A drawback to such methods, however, is that x-ray radiation used to generate the images can be a burden to the patient's health.
Magnetic resonance or nuclear spin tomography recordings (MR recordings) can be produced without any burden to the health of a patient. Such imaging techniques are suitable for displaying soft tissue. Bone structures, however, generally are poorly identified or not identifiable in MR recordings.
In order to display both bone structures and soft tissues, it may be necessary to register or fuse CT recordings or x-ray recordings to MR recordings of a patient. This, however, can incur significant costs since computer tomographs and magnetic resonance tomographs are very expensive both to purchase, maintain and operate. Further, a plurality of CT recordings typically are produced, which can place a high radiation load on the patient.
Attempts have been made to develop systems that can be used without separately detected patient body structure data, for example on the basis of generic models of image data sets for body structures. However, such systems can lack the required accuracy for the patient to be treated in each case.
EP 1 348 394 relates to a method for computer-assisted, medical navigation in which the current position of a patient or part of a patient's body and the positions of medical treatment apparatus or treatment-assisting apparatus are detected by means of a position detection unit. The detected position data are assigned to body structure data in order to jointly use the body structure data and assigned position data within the framework of treatment assistance. Body structure data are used that are obtained on the basis of a three-dimensional generic model, wherein the model is adapted by data-linking on a two-dimensional plane with patient-characteristic, two-dimensional detection data.
These generic models, however, are not primarily based on MR data sets. Therefore, generic MR data cannot be correspondingly deformed and registered to the fluoroscopic images.